The present invention relates to an image processing system of digital method having a zoom function for magnifying a picture of a partial region of a single frame displayed on a monitor screen to a whole sized screen, and particularly to a circuit for controlling a picture of a desired partial region to magnify, according to selection of an operator.
Usually, the operation of a digital image processing system includes steps of storing temporarily an image data of one field amount to a field memory, reading out the image data stored in the memory, and thereafter converting the data into an analog image signal to display on a monitor screen through a monitor driver. The zoom function means, in the art, a pictorial operation magnifying a picture of a partial region of one frame displayed on the screen of a monitor to a full-sized picture of one frame. In order to carry out such a function, the digital image processing system reads out image data stored in an address corresponding to a selected partial area of total image data in field memory, converts the read-out data to an analog image signal, thereafter outputting to a monitor through a monitor driver, by which it becomes magnified to a full-size screen on the monitor. However, a conventional zoom function as shown in FIG. 1, has a drawback that selection of a desired picture portion to magnify is considerably limited because it is constructed so as to be operated by magnifying selectively the partial picture around only five fixed locations.